Hides elements unless an Omeka user is logged in.

filter_elements.php

<?php

/**
 * Unset elements if there is not current authenticated user.
 */
function filter_elements($elementsBySet) {

    /* An array of elements in sets to be hidden from non-authenticated users. */
    $hiddenElements = array(
        'Dublin Core' => array(
            'Description',
            'Creator'
        )
    );

    if (!current_user()) {
        foreach ($hiddenElements as $setName => $elementNames) {
            foreach ($elementNames as $elementName) {
                unset($elementsBySet[$setName][$elementName]);
            }
        }
    }

    return $elementsBySet;
}

add_filter('display_elements', 'filter_elements');